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Tracking monsoon variations across India

Half the monsoon is over. The India Meteorological Department (IMD) has forecast a traditional monsoon for the second half of the season, because it did for the primary half. Aggregate statistics, nonetheless, cover the vast variation over time and geographies. While states on the east coast have obtained extra rainfall for a lot of the primary half, rainfall fizzled out on the west coast earlier than recovering in August. In flood-hit Assam and Bihar, too, the rainfall has remained within the extra class thus far.

Wide variations in monsoon precipitation over time and areas, between highs and lows and rain deficits and surpluses aren’t useful for agriculture in a rustic the place two-thirds of the inhabitants rely on farm incomes for a dwelling. The output of summer time crops comparable to rice, sugar, lentils and edible oil seeds relies on monsoon rains.

For India as a complete, quite a lot of rain appears to have fallen early within the season. For most of June, for instance, the cumulative monsoon rainfall was within the “excess” class. This signifies that India obtained rather more rainfall in June than previous statistics would have anticipated it to. A departure from the Long Period Average (LPA) of between 20% and 60% is taken into account extra rainfall. But, as June moved to July after which August, this cumulative rainfall has slowly trended in direction of regular. A rainfall departure of as much as 20% is taken into account regular. The LPA is calculated because the imply of the rainfall from 1961 to 2010.


This India-wide pattern can also be true for states comparable to Rajasthan, Madhya Pradesh, Gujarat (barring the Saurashtra and Kutch areas), Haryana and Delhi, Jharkhand, Odisha, and Gangetic West Bengal.

This hasn’t been the case in some areas of east India. In Assam, Bihar, and jap Uttar Pradesh, which have seen floods this season, cumulative rainfall within the first half of monsoon has been both extra or giant extra. Rainfall departure of above 60% of LPA is taken into account giant extra. Deviation of cumulative rainfall from regular in jap Uttar Pradesh began reducing by the tip of June, however reached the conventional vary solely by the tip of July. That isn’t the case for Bihar, the place cumulative rainfall remains to be within the extra vary. While the deviation from the LPA has been decrease in Assam in comparison with Bihar and jap Uttar Pradesh for many of this season, it was regular between the 20% and 40% vary earlier than August. Western Uttar Pradesh, however, has been rain-deficient all through this monsoon.

See Chart 2

The two coasts of India have seen barely completely different traits. Barring the Konkan and Goa area, the west coast has obtained comparatively regular monsoon rainfall this season in comparison with the states on the jap coast. The Konkan area had giant extra and extra rainfall in June, however stabilized to regular values from July. However, the coastal Karnataka area and Kerala have seen a sudden rush of rainfall in August. Coastal Karnataka was 11% rain-deficient (although throughout the regular vary) on August 1. It had a 3.6% extra by August 10. Similarly Kerala was 28% rain poor on July 28. This deficit grew to become a 0.8% surplus by August 10. This means that these two states obtained quite a lot of rain in August. This fast revival to regular ranges of monsoon rainfall explains the floods which have hit these states this month.

See Chart 3

While the west coast has seen a lower in departure from regular in July, the east coast noticed a rise. Tamil Nadu and Andhra Pradesh have each seen cumulative rainfall rise to above regular values in July, which has continued into August. Odisha, nonetheless, has seen a decline from above regular values in early June to regular values in July.

See Chart 4

Apart from inflicting floods, such uneven distribution of rain – regardless of mixture rainfall being regular – isn’t good for agriculture, in response to specialists. “Sometimes it rains 70 mm in a day and after that for 20 days there is no rain. That destroys all the crops because most farmers don’t have rain water harvesting structure,” mentioned Professor Jeet Singh Sandhu, vice chancellor of SKN Agriculture University, Jobner, Jaipur. Regular rainfall of much less depth can also be wanted for sustaining moisture within the soil for utility of fertilizers, Sandhu added.

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